1. Field of the Invention
This invention relates to two piece captive dispensing caps which utilize central plugs or posts as the major sealing means. The present invention is particularly directed towards a sealing plug manufactured with a hollow interior which is designed to balloon outwardly under internal pressure. This ballooning increases the tightness of the seal between the plug of the inner cap and the dispensing aperture of the outer cap in use. When the plug structure assembled in an outer cap on a container comes under internal pressure, the plug swells thereby increasing the effectiveness of the seal.
2. Description of the Prior Art
The use of removable caps to retain the contents of containers has been in use for many years, and many of those caps were lost or misplaced, thereby creating the need for a captive or retained cap. Many styles of retained caps have since been manufactured and the most common styles are the flip top, the twist open and close cap and the push/pull cap. Many of these caps utilize a central core or plug as the means of sealing the aperture through which the contents of the container are dispensed. As my new design in plugs can be utilized on many styles of caps, the following search is primarily directed towards captive dispensing caps having a central sealing plug, and particularly those with a hollow inner core.
The search conducted produced the following Patents:
1. A patent was issued to Gronemeyer et al, on Nov. 28, 1961, U.S. Pat. No. 3,010,619, which illustrates a hollow core plug designed to expand when the top twist open/close cap is applied and seated in the closed position.
2. U.S. Pat. No. 3,578,223, dated May 11, 1971, was issued to Armour for a partially hollow center post having a non-functional purpose on a twist-to-open cap.
3. On Aug. 21, 1956, Dahlin was issued U.S. Pat. No. 2,759,643, for "Container Closure" which contains a central hollow nozzle having dispensing apertures.
4. A patent issued to Roggenburg, Jr., on Oct. 2, 1984, U.S. Pat. No. 4,474,314, illustrates a self-closing squeeze bottle having a central vented valve.
5. The Stull patent issued on Oct. 16, 1984, U.S. Pat. No. 4,477,002, shows a two piece cap with a central solid core plug.
One major problem involving the captive dispensing cap has been the leakage of the container contents when the assembled unit comes under pressure. This leakage generally occurs between the dispensing orifice and the central sealing plug, which are not designed to accommodate an increase in internal pressure. This problem is especially obvious when the assembled filled containers are shipped by air in unpressurized cargo holds or experience an increase in temperature during transportation, both resulting in a build up of internal pressure and subsequent leakage. Some past art devices utilize pressure releasing vents, which unfortunately often release the container contents as well when the pressure increases beyond an optimum point.
The hollow central stem of Gronemeyer's patent, U.S. Pat. No. 3,010,619, is designed to expand in a different method and for a different purpose from the sealing plug of my invention. The angle of the top distal surface of the central stem of the Gronemeyer device is designed to connectively interact with the angled surface of the dispensing opening only when the side walls of the central stem are bowed. This bowing action of the walls is a functional design feature of the cap, being accomplished through the tightening action of the outer cap onto the inner cap. The central stem is in essence, too tall for the device and must be depressed and bowed to achieve a correct connection. In other words, the correct sealing apex angle of the central stem with the dispensing opening necessitates the bowing of the outer walls of the central stem or the seal would not be sufficient. Gronemeyer makes no claim as to the plug having the ability to expand when under increased internal pressure and even if expansion is possible the excess bowing of the side walls of the central stem, beyond that which it is designed, causes an adjustment in the apex angle of the stem and dispensing opening thereby creating an ineffective seal. Although the bowing action of the central stem is effective for normal sealing of the dispensing opening, it does not compensate or overcome the effect of increased internal pressure, and Gronemeyer makes no claim to the contrary.
The central stem of U.S. Pat. No. 3,578,223, although hollow, has thickened side walls not suitable or functionable to be inflated.
The Dahlin patent, U.S. Pat. No. 2,759,643, illustrates a central core having at least one dispensing aperture through the side wall, which prevents the core from expanding under pressure.
The Roggenburg, Jr. patent, U.S. Pat. No. 4,474,314, shows a central hollow core also having apertures through the side walls which again prevents expansion.
U.S. Pat. No. 4,477,002, provides an example of solid core central plugs, which effectively seal the dispensing aperture but fail to expand and effect an increase in sealing means when under pressure.
I feel my invention of the ballooning central plug overcomes the previously mentioned disadvantages of the earlier past art patents and therefore provides new and useful benefits and improvements applicable to the design of both push/pull and twist open/close captive cap closures.